Automotive battery "jumper cables" are well known for use in electrically connecting a discharged battery to a charged battery of another vehicle. This is done to derive sufficient current from the charged battery to start the vehicle having the discharged battery. Conventional "jumper cables" include a pair of electrically conductive cables, each having a pair of hand operated terminal clamps at opposed ends. The terminal clamps are typically in the form of a spring pincer with jaws at one end and handles at the other. The spring urges the jaws toward a closed position. The jaws may be forcibly separated by gripping the handles in the hand and pivoting them toward one another. The handles may be released to enable the jaws to close on the terminal of a battery. At least portions of the jaws are electrically connected to the associated conductive cable.
It is a hazardous process to connect the terminals of batteries, especially when one of the batteries is in a discharged condition. The rush of current from the charged battery to the discharged battery will often result in sparks as initial contact is made. The hazard is not necessarily from the sparks but more from the potential of igniting explosive gases that may be present about the batteries. Serious injury can occur should the explosive gases be ignited and the battery burst.
The above problem has led to development of devices for suppressing, isolating or eliminating such sparking as terminal clamps are connected to electrical power terminals. However, many such attempts result in complicated and expensive apparatus that are difficult to produce and cost prohibitive to the average consumer.
It is therefore an object of the present invention to provide a device that is relatively simple, inexpensive, easy to operate, and has the capability of eliminating an electrical spark when cable clamps are connected across electrical power terminals.
A further object is to provide such a safety device that is safe in use, being relatively automatic to open a switch and prevent current from flowing to the associated cable as the clamp handle sections are gripped, and by requiring a separate, positive action by the user to complete the circuit once the clamp is secured to the associated terminal.